Enemies
Now with Xander being the chief Slayerette and Faith being something of a psycho villain. Not Everyone is happy with our favorite couple. Here's a list of people, that Faith/Xander writers often use to make things hard on Faith and Xander...
Willow: Okay, consider Willow Faith/Xander shipper public enemy No. 1. Willow's had it in for Faith since she came to town. She thinks that Faith is taking Buffy and Xander away from her, of course she's kinda right. Think about it, Buffy and Xander have been waiting for the chance to drop Willow in a ditch and move on. Faith's gives them that opportunity. Willow is usually portrayed as jealous of Faith, or as wanting to get with Xander herself. If not jealous, Willow is often portrayed as whiny and frequently annoys Xander.
Anya: Anya's isn't necessarily an enemy of Faith/Xander. She's merely Xander's girlfriend, which means she's in the way. Most writers take one of two routes, Anya dumps Xander, or Anya merely isn't there. If Anya is an enemy in stories, she's portrayed as bitchy, or still obsessed with getting her powers back.
Wesley: Wesley is a problem for F/Xers, mostly after Faith goes rogue. He tries to bring Faith in. Before Faith went rogue, he simply tried to get Buffy and Faith to stop taking outside help. Wesley is often just some sort of comic relief, portrayed as stupid, clumsy, and merely an annoyance.
Cordelia: Cordelia is much like Wesley and Anya, as she's not much more than a minor annoyance. She's portrayed as Bitchy and out to make Xander miserable.
Buffy: Buffy was at first an ally to F/Xers, sometimes out to hook up Faith and Xander. But then she got all pissy after Faith went evil, tried to steal Angel's soul, poison Angel, kidnapped Willow and stole Buffy's body. Geez... talk about overreaction. If an enemy of F/X, Buffy is portrayed as bent on vengeance, and out to kill Faith.
More Enemies to come